actino-, actin-, actini-, -actinal, actis- +
(Greek: ray [as of light] or like a ray in form; radiance, radiation; a radiating or tentacled structure)
2. A protein forming the thin filaments in muscle fibers that are pulled on by myosin cross-bridges to cause a muscle contraction.
Some bacteria form actin tails to use for motility.3. Etymology: According to A Dictionary of Scientific Terms by I.F. Henderson (Isabella Ferguson) and W.D. Henderson; Edinburgh; Oliver and Boyd Publication, 1920; this word comes from Ancient Greek ἀκτίς, "ray", "a star-shaped spicule (zoology)" + the English chemical suffix -in, -ine.
All of the other "modern" medical dictionary sources that include this actin protein term do not make any references to any etymological origins.
2. Possessing photochemical properties.
3. Pertaining to or designating radiant energy: "An actinic ray exists in the visible and ultraviolet spectrum which produces marked chemical changes."
"Actinic is a term for ultraviolet (UV) rays from sunlight and UV lamps."
2. Actinic keratoses (solar keratoses) are precancerous growths caused by long-term sun exposure.
3. Etymology: actinic is from Greek aktis, "ray" and refers to the ultraviolet rays, as in sunlight, that can cause reaction in the skin; so, a "sunbrn" is an actinic injury while keras is a Greek element for "horn".
Solar keratoses, or senile keratosis, is more common with fair skinned and elderly people and it may be a discrete, slightly raised, red-on-pink lesion located on a sun-exposed surface.
Such conditions can be prevented by decreasing oneself to sun exposure and by wearing sunscreen.
Actinic keratoses usually can be removed by freezing with liquid nitrogen (cryotherapy); however, if a person has too many growths, a liquid or cream containing fluorouracil may be applied.
Often, during such treatment, the skin temporarily looks worse because fluorouracil causes redness, scaling, and burning of the keratoses and of the surrounding sun-damaged skin.
A relatively new drug, imiquimod, is useful in treating actinic keratoses because it helps the immune system to recognize and to destroy cancerous skin growths.
Another treatment includes cutting the keratoses away, by burning them with photodynamic therapy; that is, injecting into the bloodstream a chemical that collects in actinic keratoses and makes them more sensitive to destruction by a specialized form of light.
The related chemical elements include: actinium, thorium, palladium, uranium, neptunium, plutonium, americium, curium, berkelium, californium, einsteinium, fermium, mendelevium, nobelium, and lawrencium.
2. Exhibiting radiate form or structure; such as, the ray fungus or the sea anemone.
2. The intrinsic property in radiation that produces photochemical activity.
3. The production of chemical change by actinic radiation.
It possesses no stable isotopes and exists in nature only as a disintegration product of uranium and thorium.
Its longest lived isotope is Ac 227 with a half-life of 21.6 years. Atomic number 89; melting point 1,050°C; boiling point (estimated) 3,200°C; specific gravity (calculated) 10.07; valence 3.
2. A disease characterized by suppurative (causing pus) and granulomatous (inflammatory) lesions (abnormality of the skin or organs) in the respiratory tract, upper alimentary tract, skin, kidneys, joints, and other tissues.
Actinobacillus lignieresii infects cattle and sheep while actinobacillosis Equuli infects horses and pigs.
Actinobacillosis affects the soft tissues, often the tongue and cervical lymph nodes, where granulomatous swellings form and eventually break down to form abscesses.